The Performance and Kinetic Study of Membrane Anaerobic System (MAS) in Treating Pome

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Abstract / Synopsis

Anaerobic digestion has been proven to be the most efficient process for primary
treatment of POME. However a major problem in the anaerobic wastewater treatment
process is to maintain the sufficient quantity of active biomass in the reactor. In this study
membrane separation technology has been applied after anaerobic digestion to increase
solids retention time and improve treatment efficiency. The objectives of the study are to
evaluate the overall membrane anaerobic system (MAS) treatment efficiency and the
applicability of three known kinetic models on the system and determination of kinetic
coefficients.
The MAS consists of a cross-flow ultrafiltration membrane (PCI Micro 240) for
solid-liquid separation. Six steady states were ottained over a range of mixed liquor
suspended solids of 12,681 - 30,460 mgtl. The study showed a good fitting of the
Monod Model (91.1%), Contois Model (98.5%) and Chen and Hashimoto Model (95%) for the MAS treating raw POME at organic loadings between 1.5 kgCOD/m3/d to 6.5
kgCOD/m3/d. The growth yield coefficient Y, was found to be 0.604 kg VSSlkgCOD
while the specific microorganism decay rate was 0.099 day-to The k values were in the
range of 0.242 to 0.425 mg COD/mg VSS.d and the Pm values were between 0.145 to
0.257dail. The Monod Model and Chen and Hashimoto Model are better than the
Contois Model for solids retention time (SRT), effluent substrate concentration (S) and
substrate utilisation rate (E) estimation. Both models are able to produce a good predicted
S and E if the SRT >= 50 days. Throughout the study, the removal efficiency of COD was
83.2 to 97.97 %. The methane production rate was between 0.262 to 0.473 1/g-COD utilised/d
The MAS treatment efficiency was greatly affected by SRT and OLRs. In this
study, membrane fouling and polarization at the membrane surface played a significant
role in the formation of a strongly attached cake layer limiting membrane permeability.